GED Science Preparation Course: Earth and space science

1. Question 1 of 17

   In the water cycle, what happens when water vapor cools and forms clouds?

   • ARunoff
   • BCondensation
   • CPrecipitation
   • DEvaporation
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   Answer: B. Condensation

   Condensation is when water vapor cools and changes into liquid droplets, forming clouds.

2. Question 2 of 17

   Which process adds carbon dioxide to the atmosphere?

   • APhotosynthesis
   • BForming new rock layers
   • CPlants growing new leaves
   • DBurning fossil fuels
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   Answer: D. Burning fossil fuels

   Burning fossil fuels, respiration and decay release carbon dioxide. Photosynthesis removes it.

3. Question 3 of 17

   Why are coal, oil and natural gas called nonrenewable?

   • AThey are made in factories each year
   • BThey take millions of years to form
   • CThey cannot be burned to make energy
   • DThey are found only under the ocean floor
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   Answer: B. They take millions of years to form

   Fossil fuels formed from ancient living things over millions of years, so they cannot be replaced in a human lifetime.

4. Question 4 of 17

   What is the greenhouse effect?

   • AOcean currents carry cold water to the equator
   • BGases such as carbon dioxide trap heat near the surface
   • CThe ozone layer blocks all sunlight from reaching the ground
   • DPlants make the air warmer at night
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   Answer: B. Gases such as carbon dioxide trap heat near the surface

   Greenhouse gases such as carbon dioxide, methane and water vapor trap heat. More of them traps more heat.

5. Question 5 of 17

   What does the ozone layer do?

   • AMakes rain fall over the oceans
   • BAbsorbs much of the Sun's ultraviolet light
   • CCauses most of the weather that we feel on Earth
   • DTraps heat inside Earth's core
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   Answer: B. Absorbs much of the Sun's ultraviolet light

   The ozone layer in the stratosphere absorbs much of the Sun's ultraviolet light. Weather happens in the troposphere.

6. Question 6 of 17

   Which statement describes climate rather than weather?

   • AIt has been snowing hard here since early this morning
   • BThis city averages 30 inches of rain a year
   • CThere was a storm last night
   • DTomorrow will be windy
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   Answer: B. This city averages 30 inches of rain a year

   Climate is the average pattern over many years. Weather is the condition over hours or days.

7. Question 7 of 17

   Which layer of Earth is liquid?

   • AThe crust
   • BThe mountains
   • CThe inner core
   • DThe outer core
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   Answer: D. The outer core

   From the outside in: crust, mantle, liquid outer core and solid inner core.

8. Question 8 of 17

   Two plates push into each other. What can form at this kind of boundary?

   • AOnly new ocean floor
   • BNothing, because plates never touch
   • CMountains and volcanoes
   • DA mid-ocean ridge where plates move apart
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   Answer: C. Mountains and volcanoes

   At a convergent boundary, plates collide and form mountains, volcanoes and deep trenches.

9. Question 9 of 17

   At a transform boundary, two plates slide past each other. What is this boundary known for?

   • ATides
   • BEarthquakes
   • CNew ocean crust forming
   • DTall volcanoes from melting crust
   Show answer

   Answer: B. Earthquakes

   When plates slide past each other, stress builds and is released as earthquakes.

10. Question 10 of 17

    Melted rock cools and hardens. What type of rock forms?

    • AMetamorphic
    • BFossil
    • CIgneous
    • DSedimentary
    Show answer

    Answer: C. Igneous

    Igneous rock forms from cooled melted rock. Sedimentary rock forms from layers; metamorphic forms under heat and pressure.

11. Question 11 of 17

    Which action best reduces harm from earthquakes?

    • ABuilding levees along rivers
    • BPlanting more grass in city parks
    • CStopping the plates from moving
    • DUsing strong building codes
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    Answer: D. Using strong building codes

    We cannot stop earthquakes, but strong building codes reduce damage. Levees are for floods.

12. Question 12 of 17

    The table lists undisturbed rock layers. Which fossils are the oldest?

    Layer (top to bottom)	Fossils found
    W (top)	Seashells
    X	Fish bones
    Y	Fern leaves
    Z (bottom)	Trilobites

    • AFish bones in layer X
    • BFern leaves in layer Y
    • CTrilobites in layer Z
    • DSeashells in layer W
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    Answer: C. Trilobites in layer Z

    By the law of superposition, in undisturbed layers the lowest layer formed first and is the oldest.

13. Question 13 of 17

    A sample has 80 g of a substance with a half-life of 5,730 years. How much is left after 11,460 years?

    • A10 g
    • B40 g
    • C20 g
    • D0 g
    Show answer

    Answer: C. 20 g

    11,460 years is 2 half-lives. 80 → 40 → 20 g.

14. Question 14 of 17

    What mainly causes ocean tides on Earth?

    • AEarthquakes on the sea floor
    • BThe heat of Earth's core
    • CWind blowing over the ocean
    • DThe Moon's gravity
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    Answer: D. The Moon's gravity

    Tides are caused mainly by the pull of the Moon's gravity.

15. Question 15 of 17

    During a solar eclipse, how are the Sun, Moon and Earth lined up?

    • AThe three are not lined up
    • BThe Moon is between the Sun and Earth
    • CEarth is between the Sun and the Moon
    • DThe Sun is between Earth and the Moon
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    Answer: B. The Moon is between the Sun and Earth

    In a solar eclipse the Moon blocks the Sun. In a lunar eclipse Earth is between the Sun and the Moon.

16. Question 16 of 17

    Why does Earth have seasons?

    • AEarth's axis is tilted
    • BEarth spins once a day
    • CThe Sun's size changes each year
    • DThe Moon blocks the Sun in winter
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    Answer: A. Earth's axis is tilted

    Because the axis is tilted, each hemisphere gets more direct sunlight for part of the year.

17. Question 17 of 17

    What happens to a very massive star at the end of its life?

    • AIt grows until it becomes a whole new galaxy of stars
    • BIt shrinks and becomes a rocky planet orbiting another star
    • CIt cools slowly into a white dwarf without ever exploding
    • DIt explodes as a supernova
    Show answer

    Answer: D. It explodes as a supernova

    Very massive stars end in a supernova. A Sun-like star becomes a red giant, then a white dwarf.

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The real test: 145 on a 100–200 scale